1. FIELD OF THE INVENTION
The invention relates to an idling control for an Otto engine.
2. DESCRIPTION OF THE PRIOR ART
In order that an Otto engine running idle can take up load variations and does not stop a comparatively overrich fuel-air mixture is fed to an Otto engine. An increased production of noxious substances and, thus, environmental problems are caused. It is necessary to set the idling speed itself comparatively high. In spite of this, difficulties occur, if the motor vehicle comprises power steering or an air-conditioning system and if thereby load variations occure when running idle.
The DE-OS 33 16 660 describes an idling control of the above mentioned kind. The throttle valve can be adjusted from a stop position which corresponds to the idling nominal speed in order to keep the idling actual speed on the nominal value in case of decrease. If the actual idling speed is too high, it is possible to influence the speed of the Otto engine. The control of the throttle valve is effected in the periodically a change-over voltage is supplied to the three-way flow control valve so that an increased extent of a vacuum is applied to the cylinder unit. By this obviously a stable control cannot be guaranteed so that periodical variations of the idling speed occur.
The DE-PS 29 48 151 describes an idling adjustment, which excludes a decrease of the engine speed under the nominal idling speed. The control is carried out by means of a magnetic valve which causes the suction pipe vacuum in a positioning valve to become operative. Also in this case a stable adjustment is scarely possible.